With the rapid development of network application, a growing number of users face a problem of network link stability. A most direct way to resolve this problem is to provide a link redundancy function in a system using a link aggregation technology.
In the link aggregation technology, the Link Aggregation Control Protocol (LACP) is mainly used. The LACP is a protocol that is proposed based on the Institute of Electrical and Electronics Engineers (IEEE) 802.3ad standard to implement dynamic link aggregation. Both parties of communication exchange information with a peer device using an LACP data unit (LACPDU) to perform dynamic link aggregation and disaggregation, thereby implementing dynamic redundancy backup.
In other approaches, a storage device aggregates links in a controller using the LACP. That is, the storage device binds a group of ports in a same controller together into one logical port, to form an aggregated link between the controller and a switch. That is, communications links between the switch and all ports in the group of ports are aggregated into one logical link, and in a data transmission process, a redundant path is handed over according to a status of each physical link. When a port in the group of ports is faulty, the controller can quickly perceive that the port is faulty, and use a physical link of another port to carry a service. However, if the controller is faulty, all physical links between the controller and the switch are disconnected, and therefore there is no redundant path any more. Therefore, in the other approaches, when a single point of failure occurs on the controller of the storage device, a service link corresponding to a port of the controller is faulty, and the service is forced into interruption.